Usage of new API, cleanups (reduced)

jni/JniCallbacks.h

Index: jni/JniCallbacks.h
diff --git a/jni/JniCallbacks.h b/jni/JniCallbacks.h
index 38e520bc53732fe3ca0bb68a093426be5f0556f6..198451b490d85e6f7b9cdb52b361dbc37f335288 100644
--- a/jni/JniCallbacks.h
+++ b/jni/JniCallbacks.h
@@ -42,8 +42,8 @@ public:
 
 private:
   JavaVM* javaVM;
-  JniGlobalReference<jobject>::Ptr callbackObject;
-  JniGlobalReference<jclass>::Ptr exceptionLoggerClass;
+  const JniGlobalReference<jobject>::Ptr callbackObject;
+  const JniGlobalReference<jclass>::Ptr exceptionLoggerClass;
 };
 
 class JniEventCallback : public JniCallbackBase
@@ -65,6 +65,9 @@ class JniFilterChangeCallback : public JniCallbackBase
 public:
   JniFilterChangeCallback(JNIEnv* env, jobject callbackObject);
   void Callback(const std::string& arg, const AdblockPlus::JsValuePtr jsValue);
+
+private:
+  const JniGlobalReference<jclass>::Ptr jsValueClass;
 };
 
 class JniLogSystemCallback : public JniCallbackBase, public AdblockPlus::LogSystem
@@ -74,7 +77,7 @@ public:
   void operator()(AdblockPlus::LogSystem::LogLevel logLevel, const std::string& message, const std::string& source);
 
 private:
-  JniGlobalReference<jclass>::Ptr logLevelClass;
+  const JniGlobalReference<jclass>::Ptr logLevelClass;
 };
 
 class JniWebRequest : public JniCallbackBase, public AdblockPlus::WebRequest
@@ -86,8 +89,8 @@ public:
 private:
   jobject NewTuple(JNIEnv* env, const std::string& a, const std::string& b) const;
 
-  JniGlobalReference<jclass>::Ptr tupleClass;
-  JniGlobalReference<jclass>::Ptr serverResponseClass;
+  const JniGlobalReference<jclass>::Ptr tupleClass;
+  const JniGlobalReference<jclass>::Ptr serverResponseClass;
 };
 
 #endif /* JNICALLBACKS_H */